Counterflow leaching system



June 26, 1934. A. FLElscHER GOUNTERFLOW LEACHING SYSTEM Filed June 50, 1953 @Ms-Zz Patented June 26, 1934 UNITED BATES PATENT GF'FCE COUNTERFLOWV LEACHING SYSTEIVI poration ci Deia-ware Application June 36, 1933, Serial No. 678,419

3 Ciaims.

My invention relates to the operation of countercw system-s in which a solid containing reagent soluble values and moving in one direction through the system is contacted With a reagent 5 solution adapted to react with and bring into solution the values of the solid nov/ing in an opgposite direction. More particularly, though not exclusively, my invention relates to the described counterflow treatment of dehydrated alunite ores by a sulphuric acid solution. The solid to be treated will practically in all cases be divided into particles or lumps as by crushing and grinding and in such treatments the resultant mass Will generally have, in admixture with comparatively coarse particles (sands) and lumps, a considerable percentage of fines and slimes which is introduced into the counterlow system together with the ccarser material and will, to a large eX- tent, remain suspended in the liquid solvent and 2O travel with this solvent instead of with the mass of the ore and, as the ore mass is first introduced into contact with the solvent when the reactive constituent of the solvent is of very low concentration, these fines and slimes will, to a large eX- tent, pass from the system before their soluble values have been completely extracted from them.

The object of my invention is to obviate the losses incurred as above described and insure that the fines and slimes as Well as the coarser portions of the ore shall remain in contact with the solution for a sufficient time and under such conditions as to insure the extraction therefrom of their soluble values even though the residual particles pass from the system with the solution and my invention consists in the improvement of the counterow system by which the more or less finely divided solid is separated into two portions, one consisting of lines and slimes and the other consisting of coarser particles (sands and lumps), the coarser division of the solid or ore is fed into the counterflow system so as to meet the partly neutralized solvent at one end of the system and the :lines and slimes are fed intov the system at some point or points at a considerable distance in advance of that at which the coarser material is fed so that, if carried along by the solution moving in the opposite direction from the solid, such rines and slimes will remain in contact With the solution for a suicient time and under such. conditions as to insure the extraction of their soluble values.

My invention Will perhaps be better understood as further described in connection with the drawing which is a diagrammatic illustration of a 55 counterflow system embodying my improvement.

As indicated, the system is made up of four mixing tanks, indicated at 1, 2, 3, and 4.

A indicates a receptacle for a reactive solution from which, as indicated by dotted line B, a portion or the solvent solution is fed into tank number 4, nd a portion fed into the tank marked 3, as indicated by the dotted line marked B1; solution `Irom the tank 4 passes into tank 3, as indicated by the dotted line B2, and the solution from tank 3 passes to tank 2, as indicated by dotted line B3, 55 and solution from tank 2 passes to tank l, as indicated by the dotted line B4, While the nal pregnant solution passes from tank 1 to receptacle C, as indicated by the dotted line B5. D indicates a receptacle for more or less finely di- '70 vided solid material, such as crushed ore. From this receptacle the solid material (ore) passes to a classifier E, as indicated by the line F, and from the classifier E the coarser particles (sands and/or lumps) of ore pass to a receptacle G, as indicated by the line Fl, while the fines and slimes pass to the receptacle H, as indicated by the line F2. The sands and lumps from receptacle G pass to the tank l, as indicated by the line F3 and progressively therefrom to and through the tanks '80 3, and 4, as indicated by the lines F4, F5, F6, nnally being withdrawn from the tank 4 to a receptacle J, as indicated by the line F7. 'Ihe fines and slimes from receptacle H are fed, as shown, into tanks 2 and 3, as indicated by the lines F8 85 and F9.

In operation, the more or less sub-divided solid, dehydrated alunite ore, for example, is fed in measured quantity from the receptacle D into classier E, from which the sands and/or lumps are led into the receptacle G and the sep- ;iines and slimes are fed into the receptacle H, The sands and/or lumps are then fed into the ccunterlow system, as, for instance, into the tank l, Where it comes in contact with the reactive solution containing a low concentration of reactive solute, as, for example, in the treatment of alunite ores for the extraction of their solublc values with the solution in the stage in which its sulphuric acid content is of very low concentration, say, of the order of one to four percent by Weight and, in the best practice, this free sulphuric acid should be practically neutralized in this tank. rlhe solid material is progressively shifted from tank 1 into tanks 2, 3, and 4, as indicated, and 105 from tank 4 it is drawn ol in the best practice, practically exhausted of soluble values into a receptacle as indicated at J. The nes and slimes from receptacle H may be fed into the countercurrent system at practically any point in ad- 10 Vance of tank 1. As shown, they are fed into tanks 2 and 8.

The reactive solution, sulphuric acid solution, for example, as in the case of the treatment of alunite, which should initially have a concentration calculated to react with and bring into solution substantially all of the soluble values of the ore, is fed, as shown, into tanks 4 and 3, where it nrst contacts with partially or nearly exhausted ore and then, with progressively lessening concentration of acid, is fed through tank 2 into tank l, where the weak acid solution contacts with the fresh ore and is finally drawn oi' practically neutralized into receptacle C. The nes and slimes fed, as shown, into tanks 2 and 3, will be partially carried forward in admixture with the coarser portions of the ore and partially carried in an opposite direction with the owing solvent finally reaching tank 1, but being in Contact with the solvent in more reactive condition than it exists in tank 1, these fines and sliines will be exhausted of their soluble values before their slow settling portions escape from tank 1 with the solution withdrawn from it.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. In a counterflow leaching process in which crushed solid material containing soluble values is progressively contacted with a liquid solvent solution in such manner that the liquid solvent solution contacts first with the partially exhausted portion of the solid and nally with the portion 0f the solid containing a maximum of undissolved values, the improvement which consists in separating the more nely divided portions (fines and slimes) of the solid to be treated from the coarser portions thereof (sands and lumps) before subjecting the solid to counterow leaching, feeding the so separated sands and lumps of the solid so as to Contact first with the solution immediately before its withdrawal from the counterflow system and progressively thereafter with the flowing stream of solvent solution until withdrawn after Contact with the incoming solvent solution and feeding the separated fines and slirnes into the flowing stream of solvent solution at one or more points between that at which the sands and lumps are fed to the solution and the point at which the solids are withdrawn from the counterlow system.

2. The method of claim 1 as applied to the treatment of ores of alumina by a counterow of a sulphuric acid solution.

3. The method of claim 1 as applied to the treatment of alunite ores by a count-erow of sulphuric acid solution.

ARTHUR FLEISCHER.

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